Seasonal relationships between cyst germination and vegetative population of Scrippsiella trochoidea (Dinophyceae)

Abstract

The seasonal occurrence of vegetative cells and cysts of the dinoflagellate Scrippsiella trochoidea in the water column was investigated in Yongil Bay (southeastern coast of Korea). To measure germination ratios of cysts, cysts were isolated monthly from natural sediment samples and incubated in the laboratory. Vegetative cell numbers peaked in June to July, when the surface water temperature increased to over 18°C. Mass encystments were detected in the water column in August 1996 and July 1997, when the vegetative population flourished. Active germination was observed during the period of decreasing water temperature in September and October, when the vegetative population declined. Thus, there was an opposing pattern of seasonality in the potential germination of cysts and the proliferation of vegetative cells, whereby decreases in one paralleled increases in the other. The dormant period of cysts was ca 60 d, far longer than reported previously. Germination ratios increased in October 1996 and September 1997 after a 2 mo dormancy period following the mass encystments. Germination appears to be flexible with respect with length of dormancy and the age composition of cysts, both of which are based on the time and the scale of encystments as well as on conditions in the benthic environment.

Role of cyst germination in the bloom initiation of Alexandrium tamarense (Dinophyceae) in Masan Bay, Korea

“…Similar germination results of A. tamarense were observed in Hiroshima Bay (Itakura & Yamaguchi 2001). Interestingly, the temporal discrepancy between germination and blooming was also observed in another dinoflagellate, Scrippsiella trochoidea, from Yongil Bay on the southeastern coast of Korea (Kim & Han 2000).…”

“…Resale or republication not permitted without written consent of the publisher dance of vegetative cells was found in Korean coastal waters (Kim & Han 2000). The germination strategy of S. trochoidea thus showed a similar pattern in different geographical regions.…”

Influence of salinity on seasonal germination of resting stages and composition of microplankton on the Swedish west coast

“…Although some dinoflagellates germinate only at a particular season, Scrippsiella trochoidea is known to excyst readily and shows no strong annual germination rhythm (Binder & Anderson 1987, Nuzzo & Montresor 1999. In Onagawa Bay, Japan and Yongil Bay, Korea, S. trochoidea germinates throughout the year, even when vegetative growth is severely limited by temperature (Ishikawa & Taniguchi 1997, Kim & Han 2000. Consequently, the development of planktonic S. trochoidea populations may depend more on factors influencing growth than on factors regulating excystment.…”

Plankton biodiversity around the Salento Peninsula (South East Italy): an integrated water/sediment approach

“…Especially in marine coastal areas, the search for plankton-derived benthic cysts aims at integrating the classical approach to the study of plankton in the water column. The spread of this methodological innovation (Uye, 1985;Montresor et al, 1998;Rubino et al, 1998;Kim and Han, 2000) highlights the role of benthic resting stages in plankton dynamics.…”